Process of cracking hydrocarbon oils



Dec. 5, 19339 c. HUFF PROCESS OF CRACKING HYDROCARBON OILS 2 Sheets-Sheet 1 'Filed Feb.

Dec. 5, 1933. L. c. HUFF PROCESS OF CRACKING HYDROCARBON OILS 2 Sheets-Sheet 2 Al $4 QHVA". AI om B H di A. :RJ mm m N 7 L 272cm CHW 5 Y 5 in boiling range than gasoline, is pumped from passed into either-one of alternate chambers Patented Dec. 5, 1933 i 1,937,959 PROCESS OF cnaogl go HYDROCARBON Lyman C. Hufl, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application February 19,1930. Serial No. 429,475 3 Claims. (Cl. 196-49) This invention relates to the treatment of hy line 1 by pump 3 through line 2 and may then drocarbon oils and relates more particularly to take .one of several courses or paths through the a continuous process for the regulated thermal system. The raw oilmay be fed direct to the decomposition or cracking of petroleum products, heating tubes through line 4, controlled by valves 5 which can be'regulated to produce the maximum 5 and 6, (valves '7 and 10 remaining closed) or 6 yields of low boiling products suitable for motor by opening valve '7 the oil may be fed direct into fuel and other products resulting from cracking. the dephlegmator 8 wherein it undergoes heat In the operation of modern cracking processes, exchange with the vapors rising in the dephleg the period of operation relative to the shut-down m'ator and is thus preheated before passing into 10 or so-called clean-out period is determined not the heating tubes. Preferably, however, the raw only by the kind of oil being processed but also charging oil passes through line 2 and valve 10 by the mode of operation. Depending upon local in line 11 into the secondary or flash dephlegmator or general market conditions, the cracking process 12, being heated by the vapors arising therein. may be operated to produce motor fuel as its The raw charging oil together with reflux 5 principal product with no other products ,but formed in the secondary or flash dephlegmator coke and gas and possibly an intermediate cut 12 passes through valve 13' is picked up by pump corresponding to gas oil. With some kinds of 13 and pumped through line 14, valve 14' and line oil this kind of operation is not desirable and 9 into primary dephlegmator 8 where together in addition the local market condition may make with the refiux'formed therein it passes through 0 it necessary to produce a marketable fuel oil as line 15 and valve 15' and the combined feed is one of the major products with the minimum of forced by hot oil pump 16 through line 16, valve coke production. 16" and the heating tubes 17. The latter are The process which I am about to describe is located in a suitable furnace setting 18. The adapted to operate upon the non-residuum basis, combined oil feed heated to the conversion tem- 25 wherein the major products from the processing perature is discharged through line 19, controlled of relatively high boiling hydrocarbons are coke by valve 20 into reaction chamber 21 where the and gasoline, with the greatest economy in operreaction is completed. The vapors arising in reating cycle and low investment cost in equipment, action chamber 21 pass through line 22, controlled while on the other hand my process permits a by valve 23, into primary dephlegmator 8. As

30 more'continuous operation from the viewpoint of previously mentioned the reflux resulting from operating cycle when producing fuel oil as one condensation of the heavier components of the of the major products in addition to gasoline. vapors entering dephlegmator 8 is returned to- When operating the process on the non-residgether with the raw charging oil to the heating uum basis it can be adapted to cause the coke to tubes.

35 be deposited in a low pressure zone thereby re- The vapors leaving dephlegmator 8 and conducing q p e c s When operating on a taining the low boiling product of the process pass fuel oil basis particularly by the so-oalled flashing through line 24 and valve 25 into cooler, and contype of operation wherein the hot non-vaporized densing coil 26; the liquid resulting therefrom liquid from the reaction chamber is permitted passes into receiver 27 and may be passed through 40 to undergo substantial vaporization in a low presline 28, controlled by valve 29 to storage. A porsure zone, means-are provided for the use of altion of the low boiling product of the process may ternate flash distillation or evaporation chambers be returned by means of pump 30 through valve whereby the operating cycle is considerably 30' line 31 and valve 31' to dephlegmator 8 to lengthened, thus reducing operating costs. The assist in cooling and regulating the temperature 45 benefits to be obtained by the latter mode of in the dephlegmator and in the fractionation of operation are the production of a clean liquid the vapors therein. The uncondensable gasisreresidue highly suitable for use as fuel and conmoved from the receiver 2'1 through line 30", taining unobjectionable amounts of suspended controlled by valve 31". The gas may be used pitchy and carbonaceous particles referred to as as fuel for the system, or may be scrubbed to re- 50 7 move the low boiling liquids contained therein In order to make clear the operation of the and/or us d for other purposes. process of my invention, I will refer to the draw- The non-vaporized residue from reaction chamings, Figures 1 and 2. The raw charging oil, conber 21 passes through line 32, controlled by valve sisting for example of apetroleum fraction higher 33,- into branch lines 34, wherefrom it may be no and 36, the flow into the chambers being controlled by valves 37 and 38.

Chambers 35 and 36, which will be referred to as flash chambers, are at a substantially lower pressure than the reaction chamber, which causes the non-vaporized residue leaving the reaction chamber to undergo substantial vaporization when introduced into the flash chamber owing to the so-called latent heat contained in the residue. The degree of vaporization of the residue passing from reaction chamber 21 into the flash chambers 35 or 36 depends upon the temperature, the difierence in pressure between the reaction chamber and the flash chambers, and the average boiling point of the material sent into the flash chambers.

The operating conditions may be controlled to permit approximately forty percentby volume of vaporization when producing a fuel oil, or by increasing the temperature of the oil leaving the heating coil and consequently the temperature of the reaction chamber, complete vaporization to a coke residue may occur'in the flash chambers 35 and 36.

To further assist control of the degree of vaporization flash chambers 35 and 36 may be located in a furnace setting 39 which may be heated by independent firing or through which the flue gases from furnace setting 18 may be caused to circulate, by means not shown, around the flash chambers.

The vapors arising from the flash chambers pass through lines 40 and 41, controlled by valves 42 and 43 into line 44 and from there into flash dephlegmator 12. The incoming raw oil causes substantially complete condensation of the Vapors in flash dephlegmator 12 or, if necessary, may be augmented by the cooling efiect of portions of the light condensate from this dephlegmating zone recirculated thereto, by well known means not shown. The combined preheated raw oil and reflux condensate is pumped by means of pump 13 through line 14 into dephlegmator 8 and subsequently into the heating tubes as heretofore described. The vapors leaving the flash dephlegmator 12, consisting of a relatively small percentage of low-boiling material, pass through line 45, valve 45' and cooler and condenser 46 to be collected into receiver 47. A small proportion of uncondensable gas is removed through line 48. controlled by valve 49. The collected liquid is removed through line 50, controlled by valve 51.

One of the special features of the present inven tion is the alternate use of fla'sh chambers 35 and 36 in the operation of the process. The advantage of such alternate use is primarily to lengthen the operating cycle aITd in general render the operation of the process more economical. This feature of the invention may be adapted to either the non-residuum mode of operation or the operation wherein a liquid fuel oil residue is produced. It may also be adapted toan intermediate operation wherein a product suitable for asphalt may be produced. As the particular mode of operation depends primarly upon operating conditions, the principle of alternation applies equally to all modes of operation.

In the non-residuum type of operation the nonvaporized residue leaves reaction chamber 21 through line 32, controlled by valve 33 through line 34 into either one of the chambers, for example 35, controlled by valve 37. The'temperature maintained upon the products in the transfer line 19 and the pressure within reaction chamber 21 is such that upon the discharge of the residue into chamber 35 suflicient vaporization occurs to reduce the liquid residue to coke. By externally heating chamber 35 by means already described the other operating conditions may be modified accordingly, thus giving a wide degree of flexibility. Still another of the many suitable methods of increasing the volatilization of the residual liquid to cause its reduction to coke consists in injecting into the flash chambers 35 and 36 a portion of the vapors along with the residue by withdrawing same from reaction chamber 21, through line 32 controlled by valve 33 and also separately by means not shown in the drawings. This method not only causes increased evaporation by the addition of heat, but the introduction of the light vapors will also cause a substantial lowering of the average boiling point of the material in the flash chambers.

In making liquid residue in chamber 35 the temperature of the oil leaving the heating coil 1? and the pressure on reaction chamber 21 may be reduced accordingly and usually in this case no external heat or other auxiliary vaporizing means need be applied to the flash chamber. In making asphalt conditions intermediate between those already described may be used.

It is quite obvious in the non-residuum mode of operation that there is a great advantage in depositing the coke in a zone external to the reaction zone or in a low pressure zone as equipment costs are thereby decreased and the operating cycle is greatly increased.

In the present invention I provide means for switching or alternating the flash chambers when either one of them is filled with coke-for example, in the operation just described when chamber 35 is filled with coke the stream of nonvaporized residue. from reaction chamber 21 is diverted into flash chamber 36 after first preparing the chamber by one of several means which will be hereinafter described. Likewise, in the residuum type of operation or when making asphalt conditions arise either due to the operation or to the kind of oil being processed whereby it becomes greatly advantageous to switch or alternate the chambers and my process permits this.

In alternating the flash chambers it is first desirable to remove the air from the chamber which is to be cut into the process operation. This is done preferably by displacing the air with liquid or vapors, for example, when chamber 35 is to be cut out and chamber 36 to be cut in or introduced into the system the latter may be filled with oil and heated by means of flue gas, the oil therein being gradually displaced by residue. Preferably, the oil used should be the flashed residue product of the process itself.

Another means of cutting in the alternate chamber is to introduce steam for some time to displace the air, gently warming the chamber by flue gases and then cutting in the stream of hot liquid from the reaction chamber. Still another means of accomplishing this purpose is to gradually displace the air by the introduction of vapors, for example, from the dephlegmator 8 through valve 52' and line 52, the vapors passing either through .valve 53 and line 54, into flash chamber 35, or, through valve 55 and line 56 into chamber 36. The reflux liquid or combined feed from dephlegmator 8 may also be directed into the flash chamber 35 by diverting it from line 15 through valve 57, line 58 and valve 59, or into flash chamber 36 through valve 60 and line 61. The unvaporized reflux may be drawn out .proximately from the flash chambers through lines 62 and 63 through valves 64 and 65 and returned to the system through line 66 controlled by valve 6"! and through pump 13 in the manner heretofore described.

Another method of purging the flash chambers of air before they are cut into the system may employ uncondensed gas from the same or a diiferent process or other gas such as producer or natural gas. This gas may be introduced into the chambers by providing the proper connecting lines, not shown on the drawings, and may be so introduced either cold or, preferably, in a preheated state.

Other means of preparing the flash chamber either with regard to evacuation of the air or heating of the chambers before switching the stream of hot residuum from reaction chamber 21 are available, but those described are suflicient to show the operation. Coke if formed therein is removed from flash chambers by a cable or similar device previously placed within the chambers.

As examples of the results obtained by my process, a 24 A. P. I. gravity topped Mid-Continent crude was treated at a transfer temperature, i. e. the temperature leaving the heating element or at 19, of approximately 900 F., and the temperature in the reaction chamber was approximately 835 F.; the temperature in the top of the primary dephlegmator 8 was approximately 500 F. and that of the combined feed was approximately 750 F. The pressure upon the heating coil 1'7, the reaction chamber 21, and primary dephlegmator 8 was approximately 200 pounds per square inch. The comunication between the receiver 27 and dephlegmator 8 was open and free so that the diiference in pressure between these two elements was due only to the normal pressure drop through the condenser and connecting lines.

The amount of coke made was approximately one-quarter pound per barrel.

The pressure in flash chamber 35 and flash dephlegmator 12 was approximately 30 pounds per square inch. The temperature in flash chamber 35 was approximately 675 F. During the operation chamber 36 was cut in to prolong the a run.

The yield of products under these operating conditions was approximately 50 percent motor fuel with an initial boiling point of approximately 100 F. and an end point of approximately 437 F.; 35 percent of flashed residual fuel oil having a viscosity of approximately 300 Furol seconds at 122 F.; and approximately-10 percent of pressure-distillate bottoms of approximately 32 A. P. I. gravity; and about 5 percent coke, gas and loss.

When operating to make asphalt in the flash chambers 35 and 36 using the alternate method of operation with these flash chambers, a yield of approximately 55 percent motor fuel was obtained corresponding in boiling range to that obtained in the former operation about 20 percent of asphalt corresponding in specifications to steam-refined paving asphalt, about 15 percent of pressure-distillate bottoms of approximately 32 A. P. I. gravity, and about 10 percent coke, gas and loss. The amount of coke made was ap- 1 pounds per barrel.

When operating on the non-residuum basis making only coke, distillate and gas, approximately 63 percent of motor fuel was made equivalent in boiling range to that made in the flrst operation, approximately 10 percent of pressuredistillate bottoms, about 2'1 percent of coke, gas and loss. The amount of coke made was approximately 55 pounds per barrel and the amount of gas approximately 675 cubic feet per barrel of oil charged.

Compared with normal operation wherein the alternate flash chambers are not used, the running time on non-residuum operation would be approximately twice as long as that utilizing a single reaction chamber of equivalent capacity to one of the flash chambers. It is quite obvious that in a continuous operation the coke produced, which is normally the limitation on the operating cycle, becomes a secondary factor in the operation of my process. It is also obvious that I may use two or more flash chambers according to the concepts of my process.

While the above examples are illustrative of my process, I do not wish to be limited thereby in view of the broad scope of the invention.

I claim as my invention:

1. In an oil cracking process of the character wherein vapors produced in the process are dephlegmated in a dephlegmating zone and carbon precipitated from the cracked liquid oil in enlarged chambers which are alternately cut in and out of the cracking system for carbon deposition therein and cleaning; the method of preconditioning the chambers prior to being cut into the system and after cleaning which comprises preheating charging oil for the cracking process in said dephlegmating zone by heat exchange with the vapors therein, introducing charging oil thus preheated to the chamber to be preconditioned, and thensupplying such charging oil to the cracking system for cracking treatment therein.

2. In an oil cracking process of the character -wherein vapors produced in the process are dephlegmated in a dephlegmating zone and carbon precipitated from the cracked liquid oil in enlarged chambers which are alternately cut in and out of the cracking system for carbon deposition therein and cleaning; the method of preconditioning the chambers prior to being cut into the system and after cleaning which comprises'preheating charging oil for the cracking process by direct contact with the vapors in said dephleg- 'mating zone, passing at least a portion of the resultant mixture of preheated charging oil and reflux condensate into the chamber to be preconditioned and then supplying the mixture to the cracking system for cracking treatment therein.

3. In an oil cracking process of the character wherein vapors produced in the process are dephlegmated in a dephlegmating zone and carbon precipitated from the cracked liquid oil in enlarged chambers which are alternately cut in and out of the cracking system for carbon deposition therein and cleaning; the method of preconditioning the chambers prior to being cut into the system and after cleaning which comprises introducing thereinto reflux condensate formed in said dphlegmating zone, withdrawing the reflux condensate from the cut-out chamber being preconditioned and then returning the same to the cracking system.

LYMAN C. HUFF. 

